Plataformatec has released an important update to Devise, particularly if you’re using something other than Postgres or SQLite. They've released updates to the 1.5, 2.0, 2.1, and 2.2 levels of the library.

You might have 100% code coverage, but that doesn’t mean your tests are great. Just because a line of code is getting executed for a test doesn’t mean that you’re testing the right behavior of that code. Mutant takes care of making small changes to your code at runtime to and then makes sure your tests properly fail.

Ján Suchal created a GARelic gem, which allows you to do performance monitoring on your Rails application using Google Analytics. You can monitor things like response times for any given action, find slow page loads, and see how much time is spend in the database and view generation for each action.

If you have a data-intensive app, and you need to produce a variety of reports from different angles, maybe check out Dossier by Adam Hunter. Dossier offers a straightforward way to generate html reports out of your SQL tables.

Split, a Rack based AB testing framework, recently came out with version 0.5. If you really want full control over your AB experiments and your data, Split comes with an impressive number of features and algorithms to do it yourself.

If you need to build a Rails app that has social networking features like comments, reblogs, following/followers, and timelines you may want to check out Inkwell by Sokolov Sergey. The gem comes with models which easily can give your app this behavior.

The Social Stream gem recently hit 1.0. This gem also adds social networking features to your existing app, but takes things even further with default controllers and views, as well as a bunch of additional components, such as documents, events, links, and contacts

Since the beginning of January Tom Fakes has been writing some great blog posts on speeding up your Rails apps, from Fragment cache techniques to etags. He’s also started a free monthly newsletter called Faster Rails.

There is a vulnerability in the JSON code for Ruby on Rails which allows attackers to bypass authentication systems, inject arbitrary SQL, inject and execute arbitrary code, or perform a DoS attack on a Rails application.

The one in which we learn how to write a JSON parser in Ruby, process jobs in tests, get our apps ready for Rails 4, ignore files globally (as well as secret_token.rb), take a look at Ruby 2.0, and get our hands on the redis-sentinel gem.